**4.1 Data types, accuracy, positioning, time scale/acquisition cycles**

The data types and sources are summarized, collected and described in the following table to give a short overview:


Table 2. Data types required for control and simulation

The network model must be as actual as possible and should be updated whenever changes occur in reality. Very sensible with regard to the computation result is the information of actual or historical valve positions (open/closed); its tracing is indispensible, because wrong position will cause wrong/deviating results. The size of the network model may extend from some 1000 pipes up to 700 000 pipes (transport system to large distribution system including the transport system). The pressure range of larger networks may go down in several levels from 100 (84) bar to 0.020 bar finally at distribution level.

The data sources of different systems and their type of data which are necessary to build up a network model for simulation is shown schematically below (see figure 5). When computing the calorific value for each node (geographic position x,y) over time (t) the resulting value will be used to support the billing process.

Gas Quality Parameter Computation in Intermeshed Networks 143

So called "Reverse Feeding" to the transportation network is required to solve the problem of excess biogas production in a local area. An extra pipeline leads the biogas that has been previously compressed to an appropriate point (nearest one) of the transportation network. The level of compression depends on the pressure level of the transportation system

If biogas is fed into a distribution network it must be odorized before. Odorization adds the typical alarming and disgusting smell to the gas that warns human beings in case of leakage. If in the situation that excess biogas exists in a network area odorized biogas must be deodorized before entering the transportation network that has no odorized gas

Building a network model is a complex task. It starts first with data extraction from the geographical information system (GIS) via a special interface. This will include and deliver all pipe data, node geographic coordinates and equipment forming the basic network structure. Control equipment such as valves and controlling regulators are read or derived from GIS data; regulator devices often must be connected manually or corrected afterwards. Next the inputs and outputs of the network have to be introduced. Aside from feeder points or underground gas storage the outputs - better said the outflows – are modeled by consumers. Each consumer (up to hundreds of thousands) has his individual set of data, static or dynamic. Static data are used for long term planning for a certain scenario, dynamic data is used for short term planning (i.e. some days). When the simulation finally starts the correct pressure data – at least for the most important points - must be given to the simulator. Consumer data, valve position and pressure data must be taken from different IT-systems: Energy Data

Transport networks are designed to transport gas over longer distance. They are equipped with remote control which transmits all relevant data to the control centre. From the point of view of modeling these networks have an excellent information base for a moderate number of pipes and nodes (measurement points) making modeling straightforward and easy. The

Distribution networks are designed to transport gas over shorter distance, e.g. within a city. They are equipped also with remote control, but only important data is transmitted to the control center. The amount of data handled may be subject to changes in the future when for each customer Smart Metering and on upper level Smart Grid will be introduced. From the point of view of modeling the distribution networks have an acceptable information base for

(odorization will be added downstream at the distribution level, only).

Management (EDM) system and Process Control system (SCADA).

network structure of a transport system tends to be sparsely intermeshed.

**5.3 Reverse feeding to high pressure trunk lines** 

(occasionally this can be up to 80 bar).

**5.4 Odorization and deodorization** 

**6. Network modeling, simulation** 

**6.1 Transport networks** 

**6.2 Distribution networks** 
